The invention relates to a fastener with barb-like projections for improving anchoring.
As is known, either fastener or glue or both may be used for joining wooden panels. If nails are used, the nail heads remain visible, while if they are countersunk, they have to be spackled. Thus, the use of nails is limited to those components where nails do not constitute a disadvantage. The gluing together of wooden panels requires great care with regard to the glue, the degree of dryness of both panels, the tension characteristics of the types of wood to be joined together, and so on. These problems are exacerbated in the case of wall, ceiling and floor panels because the framing timber must be selected, stored, and worked with the greatest care. To prevent warping, parallel joined panels must be constructed completely symmetrically, i.e. both panels must have symmetrical dimensions, particularly the thickness. They must have matching density or specific gravity, matching expansion and shrinkage characteristics for the wood, as well as matching moisture absorption capacity. In addition, the spacing timbers located between the two panels, i.e. the so-called framing timber must be free from any warping tendencies and well seasoned, while also having the correct moisture value. Otherwise, the panels will warp. Thus, the conditions of the wooden members to be joined together constitute important parameters for the use of glue.
A classic example of the problems and difficulties of gluing is provided by door panels of hollow doors. Such doors are really nothing more than hollow glued shell elements closed on all sides. Apart from an esthetically attractive appearance, such doors have the advantage that their dimensions are standardized and the framing timber manufacturer can select and purchase in a planned manner. However, warping damage frequently leaves such doors distorted, so that they no longer close properly and also have an unattractive appearance. In addition, with hollow doors, the sound attenuation is very small because the combined thickness of the two door panels is only about 10% of the total door thickness, so that the door panels are rather thin. In addition, due to above-mentioned necessary symmetry for gluing purposes, the two door panels must have precisely the same thickness, and this has an even less favourable effect on the sound attenuation. Such panels can only have an effective sound attenuation if, for reasons pertaining to natural frequencies or resonances, the two panels have different thicknesses. This applies correspondingly in the case of wall panels which, due to the lack of symmetry, cannot be glued if the two wooden panels have different thicknesses, as would be necessary to obtain the desired sound attenuation. It must also be remembered that through gluing adjacent wooden members a homogeneous joint is formed, which is also disadvantageous from the standpoint of sound insulation.
Furthermore, when gluing panels for walls, floors, or ceilings, large quantities of wood with very varied dimensions must be carefully stored for many years. This requires large climatically controlled storage areas and drying plants. In addition, it is necessary to have air conditioned processing workshops as well as expensive machines such as hot process daylight presses or high frequency gluing installations. Thus, gluing is not only problematical and inadequate from the technical standpoint, it is in fact also very time-consuming and expensive both as regards storing and processing. The result of all these disadvantages of gluing is that glued wood shell elements are relatively expensive as compared to such elements made from inorganic materials.
A further serious disadvantage of nails is that the hitherto known wire locking nails, despite the tooth-like projections provided in the nail shaft, e.g. by means of grooves, are only inadequately anchored in the wooden panels, i.e. they easily become loose or can be removed from the panels even by a relatively small force.